Cook the potato gnocchi according to the package directions. Drain and set aside.
Pat the chicken thighs dry and season both sides with salt, black pepper, and paprika.
Heat 2 tablespoons of butter or ghee in a large skillet over medium-high heat.
Add the chicken thighs and cook for about 5–10 minutes per side, or until golden brown and cooked through. Transfer the chicken to a plate and set aside.
Reduce the heat to medium and melt the remaining 3 tablespoons of butter in the same skillet.
Add the minced garlic and Italian seasoning, followed by the diced onion and mushrooms. Sauté for 3–4 minutes, until the onion is translucent and the mushrooms are tender.
Pour in the chicken broth and whisk for about 1 minute, allowing it to heat through.
Slowly pour in the half-and-half or cream while whisking continuously. Add the mozzarella and whisk for 2–3 minutes, until the cheese melts and the sauce begins to thicken.
Stir the cooked gnocchi and spinach into the sauce. Cook until the spinach wilts, then season with additional salt and pepper if needed.
Return the chicken thighs to the skillet and simmer gently for about 2 minutes to warm everything through. This Garlic Chicken Gnocchi Skillet is best served hot.
Garnish with fresh parsley, Parmesan, and red pepper chili flakes if desired.